We discuss the principles of distributed transactions, then we define an operational model which meets the basic requirements and we give a prototyping implementation for it in join-calculus. Our model:

1. extends BizTalk with multiway transactions;
2. it exploits an original algorithm, for distributed commit;
3. it can deal with dynamically changing communication topology;
4. it is almost language-independent.

In fact, the model is based on a two-level classification of resources, which should be easily conveyed to distributed calculi and languages, providing them with a uniform transactional mechanism.